Note: Descriptions are shown in the official language in which they were submitted.
WO95/05116 2 ~ 6 8 9 6 9 PCT~S94/09354
-- 1 --
DEFLECTABLE CA~n~.~K
Background
This invention relates to deflectable catheters.
In order to facilitate the advancement of
catheters through a body lumen (e.g., an artery)
deflectable catheters have been developed. The
simultaneous application of torque at the proximal end of
the catheter and the ability to selectively deflect the
lO distal tip of the catheter in a desired direction permits
the physician to adjust the direction of advancement of
the distal end of the catheter, as well as to position
the distal portion of the catheter during e.g., an
electrophysiology procedure.
A surgeon may manipulate the proximal end of the
catheter to guide the catheter through a patient's
vasculature. The deflection of the distal tip is
typically provided by a pull wire that is attached at the
distal end of the catheter and extends to a control
20 handle that controls the application of tension on the
pull wire.
In electrophysiology catheter designs it is
critically important to have sufficient flexibility in
the catheter shaft so that when the catheter is advanced
25 through a blood vessel the catheter may follow the
inherent curvature of the vessel without puncturing the
vessel wall.
In order to maneuver around turns and bends in the
vasculature, the surgeon observes the catheter
30 fluoroscopically, and selectively deflects the tip and
rotates the proximal end of the catheter shaft. However,
the ability to control the precise position of the distal
end of the catheter ~ep~n~c on the fidelity of the
catheter's transmission of the forces exerted at the
35 proximal end to the distal tip.
woss/os116 PCT~S94/09354 -
2~3~6~
Without high fidelity torque trAn~ifision, the
surgeon is unable to control the catheter tip and at best
only delays an operating procedure, and at worst may
cause the distal tip of the catheter to cause trauma to a
5 patient.
,Su~unarv
In general, the invention concerns an axially
elongated steerable catheter of the type having a distal
tip portion deflectable in a plane in response to a pull
lO wire within the catheter and capable of being torqued at
its proximal portion to change the rotational orientation
of the tip portion about the longitll~;nAl axis. The
catheter includes: an elongated flexible outer hollow
catheter body; a deflectable tip portion deflectable
15 relative to the hollow catheter body; and a pull wire
ext~n~;ng through the catheter to a region on the
deflectable tip portion distal of the region about which
the tip portion deflects. The pull wire is arranged to
apply tension on the deflectable portion to produce tip
20 deflection.
One aspect of the invention features an elongated
wound wire coil exten~;ng through the hollow catheter
body of the steerable catheter. The coil is constructed
and arranged to enable the catheter body to withstand
25 reactive compressive load without distortion during
application of tension on the pull wire and to transmit
torque along the longitll~;nAl axis from the proximal
portion to the distal tip portion of the catheter to
e~h~ns~ the fidelity of rotational positioning of the
30 distal tip portion in response to change of rotational
orientation of the proximal portion of the catheter. The
coil is in torque-transmitting relationship with the
interior of the hollow shaft substantially along the
common length of the catheter body and the coil, so that
35 when the catheter is bent within the body such that
WO95/05116 ~16 8 9 ~ 9 i ~ J l PCT~$94/09354~
- 3 -
rotational drag is imposed on the catheter body that
tends to cause the distal tip portion to lag the proximal
portion, the coil applies torque to the hollow shaft to
provide high fidelity transmission of rotational position
5 from the proximal end to the distal portion of the
catheter.
A catheter with a high fidelity transmission of
torque from the proximal end to the distal tip portion
permits a surgeon to precisely conLLol the position of
10 the catheter tip during advancement of the catheter
through a body lumen, during a surgical procedure, such
as electrophysiological mapping or ablation of heart
tissue. The catheter achieves high torque transmission
without sacrificing flexibility of the catheter shaft, so
15 that the catheter may easily follow the inherent
tortuosity of a patient's vasculature without risk of
puncture to the patient's v~c~
Various embodiments of this aspect of the
invention include one or more of the following features.
The coil is formed separately from the hollow
catheter body. The coil includes an elongated tightly
wound wire. The ratio of the clearance, between the
outer surface of the coil and the internal surface of the
catheter body and the transverse cross-sectional
25 dimension of the wire in the radial direction of the
coil, is less than 0.9 if the wire has a rectangular
transverse cross-section, and is less than 0.6 if the
wire has a circular transverse cross-section.
The proximal end of the coil is fixedly attached
30 to the proximal end of the catheter body. The distal end
of the coil is fixedly attached to the distal end of the
catheter body. The coil has an outside diameter that is
O at most O.OlO inch less than the internal diameter of the
catheter body. The surfaces are exposed and adapted for
35 torque-transmitting contact with each other in regions
WO95/05116 ~ ~ 6 8 ~ 6 9 PCT~S94/093~4
-- 4
where the catheter is bent. The coefficient of friction
between the internal surface of the hollow catheter body
and the outside surface of the coil is at least 0.3. The
internal surface of the hollow catheter body is a
5 urethane polymer, and the coil is metal. At least a
distal portion of the coil includes a flattened region
constructed and arranged to facilitate bending of the
coil in the direction of deflection of the distal portion
when tension is applied to the pull wire.
The catheter is an electrophysiology catheter
further comprising at least one electrode mounted on the
deflectable tip portion, and an insulated conducting wire
fixedly attached to the electrode extends through the
catheter to the proximal end. The conducting wire is for
lS delivering electrical signals to and from the electrode
for mapping or ablation of myocardium tissue.
The catheter is an electrophysiology catheter that
further includes at least one electrode mounted on the
deflectable tip portion, and an insulated conducting wire
20 that is fixedly attached to the electrode and extends
through the catheter to the proximal end. The conducting
wire delivers electrical signals to and from the
electrode for mapping or ablation of myocardium tissue.
The pull wire is generally coaxial with the
25 elongated flexible hollow catheter body. The catheter
body comprises a braided metal wire shaft with a
polymeric coating. The proximal tip portion is
constructed from a material more flexible than the
catheter body. The proximal end of the deflectable tip
30 portion is bonded to the distal end of the catheter body.
A safety wire is fixedly attached to both the deflectable
tip portion and the catheter body for providing flexible
attachment therebetween.
In another aspect, the invention features an
35 actuating member mounted to move relative to the catheter
-
woss/os116 PCT~S94/09354
body. The actuating member includes a pulley surface
bodily movable therewith. The pull wire is trained about
the pulley surface such that movement of the actuating
member a given distance, relative to the catheter body,
5 causes the pull wire to move a substantially greater
distance than the given distance, thereby applying
tension on the deflectable portion to produce tip
deflection.
In preferred embodiments of this aspect of the
lO invention the pulley surface is defined by a rigid
formation rigidly joined to the actuating member, about
which relative sliding motion of the pull wire occurs
during actuation.
In another aspect the invention features steerable
15 catheters and especially electrophysiology catheters of
the type described which include a control handle at the
proximal end of the catheter. The control handle
includes a housing having a piston chamber therein and a
piston that has proximal and distal ends and a
20 longitl~;n~l bore therethrough. The piston is slidably
mounted in the piston chamber. The distal end of the
piston is fixedly coupled to the proximal end of the
catheter body. The proximal end of the pull wire is
attached to the housing at a location proximal to the
25 piston chamber, and extends through the bore in the
piston, the interior of the catheter body and into the
distal lumen of the catheter tip. Longitll~; n~ 1 movement
of the piston relative to the housing results in
deflection of the catheter tip.
In another aspect, the invention features
catheters of the type described which have a lubricous
sheath that has a lumen with an inner diameter sized to
substantially match the outer diameter of the pull wire.
The sheath is disposed around the pull wire and extends
35 from a location proximal of the proximal end of the
WO95/05116 2 ~ 6 ~ 9 6 9 PCT~S94/09354 -
- 6 -
piston chamber to a distal location spaced proximally
from the distal end of the pull wire by a distance
greater than or equal to-the maximum operating length of
longitll~; nA 1 movement of the piston relative to the
5 housing.
Other features and advantages of the invention
will become apparent from the following description and
from the claims.
Descri~tion
Fig. 1 is a diagrammatic illustration of a
deflectable catheter of the invention disposed within the
body of a patient.
Fig. 2 is a side view of the deflectable catheter
of Fig. 1 under deflection and with torque applied to its
15 proximal end.
Fig. 3 is a side view, in partial cutaway, of the
deflectable catheter in Fig.1.
Fig. 4 is an enlarged cross-sectional side view of
the distal portion of the deflectable catheter of Fig. 1.
Fig. 4A is a transverse cross-sectional view of
the distal tip portion of the catheter shown in Fig. 4,
taken along the line 4A-4A.
Fig. 4B is a transverse cross-sectional view of
the distal end of the proximal portion of the catheter
25 shown in Fig. 4, taken along the line 4B-4B.
Fig. 5 is a side view of a portion of a wire coil
according to the invention.
Fig. 5A is a side view of a distal portion of a
wire coil of the invention with a flattened region.
Fig. 5B is a cross-sectional view of the wire coil
in Fig. 5A, taken along the line 5B-5B.
Fig. 6 is an enlarged cross-sectional view of the
handle portion of the catheter in Fig. 1.
wosstosll6 PCT~S94/09354
~68969
Fig. 7 is a further enlarged cross-sectional view
of a region of the handle portion of the catheter shown
in Fig. 5.
Fig. 8 is a side view, partially broken away, of a
5 deflectable catheter with an actuating handle in an un-
deflected position.
Fig. 9 is a side view, partially broken away, of
the deflectable catheter of Fig. 8 in a deflected
position.
Fig. 9A is a transverse cross-sectional view on an
enlarged scale taken along the line 9A-9A of Fig. 8.
Fig. 9B is a cross-sectional view on an enlarged
scale of the portion of the device in Fig. 8, encircled
by dotted lines.
Referring to Fig. 1 r in an electrophysiology
procedure, a deflect--le catheter 10 is intr3duced
through an illLLod~cer sheath into the right femoral
artery of a patient 12 by use of the Seldinger techn i ~ue
(alternatively, the catheter may be introduced through
20 the left femoral artery, or the right or left femoral
veins ~ep~n~; ng upon the region of the heart to be
accessed). A surgeon advances the catheter under
fluoroscopic guidance through the patient's vasculature
by simultaneously deflecting the distal tip of the
25 catheter and applying torque to the prn~;~l end of the
catheter.
~ he catheter is advanced until the distal tip
portion 16 of the catheter is positioned adjacent the
region of the heart 15 (e.g., under the mitral valve 17
30 in left ventricle 19) that is to be mapped or ablated
using electrodes that are disposed at the distal portion
- of the catheter. The deflectability of the catheter
permits the surgeon to accurately position the electrodes
against the desired portion of the heart wall.
WO95/05116 ~1 6 8 ~ ~ ~ PCT~S94/09354 -
- 8 -
The inventors have discovered a catheter
construction in which the catheter shaft cooperates with
an internal, elongated wire coil that is sized to
substantially correspond to the internal diameter of the
5 catheter shaft, and that engages with the material
substance of the outer catheter body to achieve high
fidelity transmission of rotational position from the
proximal end to the tip of the catheter.
As the catheter is advanced through the aortic
10 arch 14, the catheter bends significantly (e.g., about
180) to follow the natural curvature of the aortic arch,
in which case the longitll~; nA 1 portion of the catheter,
inside the deflected region, is under axial compression,
while the outer portion is under tension. The deflected
15 region tends to resist the transmission of torque from
the proximal end to the distal tip portion 16 of the
catheter which is confined within the lumen of the aorta.
When torque is applied to the proximal end of the
catheter shaft, the shaft tends to rotate the entire
20 deflected region about the proximal axis of the catheter
in the direction of the applied torque. However, the
catheter shaft is confined within the vessel lumen and
cannot rotate without Lu~L~ing the lumen wall. The
deflected region of the catheter rotates as soon as
25 sufficient tor~ue is generated to place into compression
the longi~ ; nA 1 portion of the catheter that was under
tension, and vice versa.
As shown in Fig. 2, if the deflected catheter is
divided along plane 18, which passes through the axis of
30 the catheter and is perpendicular to the plane of
deflection, the portion 20 of the catheter inside the
region of deflection is under axial compression, while
the portion 22 is under axial tension. When torque
(indicated by circular arrow 24) is applied to the
35 proximal end of the catheter, for the tip to rotate the
wo 9s/n5ll6 2 1 6 ~ 9 6 ~ PCT~59Jl09351
_ g _
torque transmission of the catheter shaft must be
sufficient to put portion 22 into axial compression and
portion 20 into axial tension.
If the torsional strength of the catheter shaft is
5 not sufficient to appropriately configure portions 20 and
22, the catheter æhaft will tend to elastically deform
and thereby store the applied torsional energy until
sufficient force is generated to rotate the tip. This
causes a lag in the rotation of the tip relative to the
10 proximal end which h;n~ers the surgeon's ability to
precisely position the catheter during advancement of the
catheter and during a surgical procedure.
Referring to Fig. 3, deflectable catheter 10
includes an elongated flexible outer hollow catheter body
15 30, a deflectable distal tip portion 32, and a h~n~le 34
at the proximal end of the catheter. The h~n~ 1 e includes
a cylindrical housing 36 and a piston 3~ hat is slidably
disposed within a cavity of the housing. Preferably, the
handle and piston are formed from acetal, e.g., DELRIN~.
The length of the catheter body is about 48
inches, while the length of the catheter tip is typically
between 1~ and 3 inches. The outer diameter of the
catheter body is typically about 7 French, and the outer
diameter of the catheter tip is typically about 6 French.
25 Of course, the choice of the catheter dimensions depends
critically upon the anatomy of the patient and the type
of procedure to be performed.
In a preferred construction, the catheter body 30
includes a stainless steel braid of counter-wound double
30 wires with a pick count (i.e., the number of times that
wires cross a unit of tube length) of about 32-34 times
per inch. The stainless steel wires are braided over a
polyurethane tube which is subsequently over-extruded
with a polyurethane coating that bonds through the braid
W095/05116 PCT~S94/09354 -
21~89~
I _ !;
-- 10 --
to the inner tubing to form a unitary structure with a
hardness of about D70.
Three ring electrodes 40, 42, and 44, are disposed
along the length of the catheter tip. The electrodes are
5 mounted on the tip so that the outer surface of the
electrodes form a continuous surface with the surface of
the tip. A rounded tip electrode 46 is mounted on the
distal end of the catheter.
Referring to Fig. 4, catheter tip 32 includes a
10 short section of flexible tubing 47 which has a pair of
non-coaxial lumens 48 and 50. Tubing 47 is formed from a
polyurethane extrusion and is preferably more flexible
than the catheter body 30; e.g., the tip portion
preferably has a hardness of about D60.
The proximal end of th~ catheter tip 32 includes
an outer circumferential notch 52 with an outer diameter
that is sized to be snugly inserted within the lumen of
the catheter body 30. The catheter tip 32 is then ho~e~
to the catheter body with a conventional adhesive.
A pull wire 54, formed from nitinol or, e.g.,
stainless steel, extends from the control handle 34,
through the lumen of the catheter body 30, and into lumen
48 of the catheter tip to a position near the distal end
of the catheter. The pull wire 54 is crimped onto a
25 stainless steel hypotube 56 which is welded to a short
length (e.g., 0.2 inches) of stainless steel ribbon 58 to
form a "T" structure. The ribbon sits within an opening
60 in the wall of catheter tip 32. The ribbon is larger
than the opening which extends into lumen 48. The ribbon
30 is bonded to the catheter tip by filling the opening with
a biocompatible adhesive.
The pull wire is preferably surrounded by a teflon
sheath 62. The sheath extends from a location near the
proximal end of the piston chamber to a distal location
35 that is spaced proximally of the distal end of the pull
woss/05116 ~ ~16 ~ 9 6 9 pcT~s94lo93s4
-- 11 --
wire by at least a distance equal to the maximum
operating length of longitll~; n~ 1 movement of the piston
relative to the housing (e.g., ~ to ~ inch). The sheath
provides lubricity for the movement of the pull wire, and
5 also serves to maintain the pull wire in generally
coaxial relation with the catheter body 30.
Electrode lead wires 64 extend from the handle 34,
through the catheter body and into lumen 50 of the
catheter tip. The lead wires are soldered to the
10 electrodes in a conventional manner.
A proximal safety wire 66 is attached to the tip
electrode 46 and extends to a short length (e.g., % inch)
of teflon tubing 68. The proximal safety wire is folded
between the outer surface of notch 52 and the inside
15 surface of the distal end of the catheter body 30. The
proximal safety wire is further wedged between the
proximal edge of the catheter tip and the distal edge of
the teflon tubing 68. The outer surface of the teflon
tubing is glued to the inside surface of the catheter
20 body.
A ~co~ safety wire 70 is attached to the tip
electrode 46 and extends to the ribbon 58. The second
safety wire is folded on itself, distally of the ribbon,
to form a loop which is potted in the opening 60, and
25 glued in place with the biocompatible adhesive described
above.
A closely wound spring coil 72, shown in greater
detail in Fig. 5, is disposed within the lumen of the
catheter body 30. The proximal end of the teflon tubing
30 abuts against the distal end of coil 72. The spring coil
- 72 has an inside diameter of about 0.038 inch and an
outside diameter of about 0.058 inch, and fits closely
within the inside diameter of the shaft 30, which is
about 0.059-0.062 inch. The coil is made from e.g., 302
35 stainless steel wire that may have a circular cross-
WO95/05116 ~ PCT~S94/09354 -
21~89~
.
~ - ~2 -
section, although a wire with a rectangular cross-section
may be preferable. The coil extends distally from the
proximal tip of catheter body 30 to near the teflon tube
68. The coil may also be fabricated from other spring-
5 like materials, such as nitinol.
During fabrication of catheter lO, the catheter
body 30 slides over a tip assembly that includes catheter
tip 32 with the ring and tip electrodes, the pull wire,
the safety wires and the electrical lead wires. All of
lO the wires are subsequently pulled through catheter body
30. The spring coil slips over the proximal end of the
pull wire and over the electrical lead wires and into the
catheter body.
As shown in Figs. 6 and 7, the proximal end of the
15 catheter body 30, with the coil disposed therein, fits
with a bore 74 inside the piston 38 and abuts against a
lip 76 that consists of a region of the piston in which
the diameter of piston bore 74 is re~tlc~. The catheter
body is attached at the proximal end to the piston using,
20 e.g., a cyanoacrylate adhesive 79.
The coil structure provides a highly efficient
transmission of torque (e.g., around curves) because the
direction of the applied torque substantially corresponds
to the incompressible axis of the coiled wire.
In a presently preferred embodiment, the coil is
attached to the catheter body 30, which allows a certain
amount of stretch in the portion of the coils on the
outside portion of a bent region of the catheter body,
thereby achieving a high flexibility while providing the
30 efficient torque-transmitting capability of the coil. In
other words, as the catheter body is bent e.g., through
the aortic arch, the upper part of the coil opens up to
maintain the flexibility, but the inner portion of the
coil is tight in compression. In this position, the
35 coil, together with the catheter body, are able to
_ woss/osll6 PCT~S94/09354
2~68g6~
- 13 -
transmit torsional and tensile forces exerted on the
proximal end of the catheter.
The spring coil 72 cooperates with the catheter
body 30 in a self-correcting, torque-transmitting
5 relationship. When the catheter is disposed within a
body lumen (e.g., an artery), the inherent curvature of
the body lumen causes the outer surface of the steel coil
to frictionally engage the internal polyurethane surface
of the catheter body 30. This frictional engagement
lO permits the coil to cooperatively transmit torque with
the catheter body from the proximal end to the distal end
of the catheter.
The coefficient of friction of the internal
surface of the catheter body is therefore a critical
15 design choice for certain preferred embodim~nts of the
catheter. The coefficient of friction of the internal
surface of the catheter body should be at least about 0.3
to permit adequate torque transmission between the coil
and the catheter body. The coil should be appropriately
20 sized to achieve optimal engagement between the outside
surface of the coil and the internal surface of the
catheter body. The outside diameter of the coil should
be at most O.OlO inch less than the inside diameter of
the catheter body for a catheter body with an internal
25 diameter of about 0.063 inch.
In addition, the close fit between the outer
diameter of the coil and the inner diameter of the
catheter body prevents the individual coils of the spring
coil from slipping relative to one another when the
30 catheter is bent, and thus prevents the coil from t~n~;ng
to buckle under the compressive loads associated with the
advAnc~m~nt of the catheter and with the deflection of
the distal tip portion.
In this regard, a critical feature of preferred
35 embodiments of the catheter design is the ratio of the
woss/os116 PCT~S94/09354 -
~8969
- 14 -
clearance (i.e., the difference between the inner
diameter of the shaft and the outer diameter of the coil)
to the wire diameter of the coil. The ratio of the
clearance to the coil wire diameter is preferably less
5 than about 0.9 for wires with a rectangular cross-
section, while for coil wires with a circular cross-
section, the ratio of the clearance to wire diameter is
preferably less than about 0.6.
In other words, the coil, in a sense, compensates
lO for the low compressive strength of the catheter body,
while the catheter body compensates for the low shear
strength of the coil, to provide a catheter that permits
a surgeon to precisely control the position of the distal
tip portion of the catheter.
While in the presently preferred embodiment the
proximal end only of the coil is securely attached to the
catheter body, it is within the scope of broader aspects
of the invention to attach either the distal or proximal
ends of the coil to the catheter body. It is also within
20 the scope of broader aspects of the invention to
construct the coil integrally with or adhered to the
catheter body.
In certain preferred embodiments the distal
portion (e.g., the distal lO cm) of the coil has a
25 flattened region 75, as shown in Figs. 5A and 5B. The
flat consists of a portion of the coil that has been
ground away by conventional means to cause a preferential
region of we~knps-c in the distal portion of the coil. Up
to about half of the diameter of the wire of the coil may
30 be ground away, as shown in Fig. 5B. The coil is
securely positioned in the catheter body so that the
outer surface of flattened region is facing the direction
that the distal portion deflects in response to tension
applied to the pull wire (i.e., the flat would be facing
35 toward the bottom of the page in Fig. 3, or alternatively
wos5/051l6 ~16 ~ 9 6 9 PCT~S94/09354
would be facing toward the top of the page in Fig. 4).
This flattened portion facilitates bending of the
catheter in the preferred deflection direction.
Referring to Fig. 7, inner and outer layers 81 and
5 83, respectively, of teflon shrink tubing surround the
proximal end of the catheter æhaft. The inner tubing 81
extends to location 85 on the catheter body, while the
outer tubing 83 extends to a location 87, proximal of
location 85.
The handle includes a cylindrical housing 36 that
has a piston chamber 78 at the proximal end and a
connector chamber 80 at the proximal end. There is an
axial passage 82 and an offset passage 84 connecting the
piston and connector chambers. The housing is generally
15 symmetrical about its longitll~;n~l axis, allowing the
handle to be freely rotated without altering convenience
or quality of ~o~lLLol.
The piston includes a circumferential O-ring notch
86 that carries an O-ring 88 to provide a watertight seal
20 between the piston and the wall of the piston chamber.
The piston includes an upper slot 90 that extends
along a portion of its length proximal of the o-ring
notch. A set screw 92 extends from the wall of the
housing into the slot. The set screw restricts the
25 longitlld;~l movement of the piston by engaging the
proximal and distal ends of the slot.
A lower slot 91 is disposed on the opposite side
of the piston as the upper slot. Within the lower slot
are two adjacent, short (e.g., ~ inch long) pieces of
30 teflon tubing that provide a lubricous surface to
- facilitate axial movement of the piston with respect to
the handle housing.
The distal end of the piston extends beyond the
distal end of the housing so that it may be manually
35 controlled by a user. An annular thumbrest 94 is
WO95/05116 ~ PCT~S94/09354 -
- 16 -
attached to the distal end of the piston to facilitate
axial movement of the piston.
The pull wire extends through the axial bore of
the piston and is attached to the housing by an Anchor
5 96. The ~n~hor extends into a transverse hole in the
portion of the housing between the connector and the
piston chambers. The anchor blocks the axial passage,
but not the offset passage. The anchor is rotatable
within the hole, but fits snugly so that it does not
lO rotate freely.
The anchor includes a transversely exte~ing hole
that may be rotated into alignment with the axial
passage. To secure the pull wire to the anchor, the pull
wire is p~ce~ through the axial passage and the
15 transversely ext~n~ing hole in the anchor, and the anchor
is rotated, by means of a flat screw driver slot 98, to
wedge the pull wire between the anchor and the wall of
the housing. Tension on the pull wire may be adjusted by
rotation of the anchor.
In use, the catheter tip may be curved or bent to
steer the tip by gripping the control handle housing and
moving the piston distally out of the piston chamber.
Because the catheter body is attached to the piston and
the pull wire is attached to the housing, pushing
25 distally on the thumbrest causes movement of the pull
wire with respect to the catheter body and tip, thereby
pulling the catheter tip proximally toward the handle.
Because the pull wire is attached to one side of the
catheter tip, the tip bends preferentially in the
30 direction of attachment (i.e., as shown by the dotted
line in Fig. 3) to accommodate the force exerted on it.
By maint~;n;ng the pull wire in coaxial relation
with the catheter body, the length of the pull wire and
on-axis length of the catheter body are the same, whether
35 the catheter body extends around a curve or not. In this
WO95/05ll6 21 6 ~ g 6 ~ PCT~594/~9354
- 17 -
arrangement, less energy is required for rotation of the
catheter tip. This allows the tip to be more responsive
to rotation of the handle and therefore more easily
controlled.
~ 5 Electrode lead wires 64 extend from the catheter
body proximally through the axial bore of the piston and
conn~ctor chambers, and into the co~nector chamber.
Preferably a teflon sheath surrounds and protects the
lead wires in the piston chamber. Within the connector
10 chamber, the lead wires and the surrounding sheath are
bowed slightly to provide slack as the catheter is
manipulated.
In the connector chamber, the lead wires are
connected to a rotary connector 100. The rotary
15 connector includes a conventional cylindrical male plug
102 (e.g., a NEXUS~ plug) that extends proximally from
the handle housing. The plug has a series of termi n~ 1 c
along its length, each of which is connected to a
separate lead wire within the connector chamber. These
20 terminals operate independently of each other and allow
separate electrical signals to be transmitted through the
connector simultaneously.
Other embodiments are within the scope of the
claims.
For example, handle 34 may be replaced with a
snare handle 110, shown in Fig. 8, and described in U.S.
Serial No. 08/109,609, filed on August 19, 1993 by Craig
R. Kline and assigned to the present assignee.
Referring to Figs. 8 and 10, the snare handle
30 advances and withdraws pull wire 54 within catheter body
30, which is bonded to the distal end 150 of the h~n~le
body 118. The proximal end of pull wire 54 is fixed to
nose 116 of handle body 118. By pulling back on the
finger handle 137 relative to the handle body 118 in the
35 distal direction indicated by arrow 111, the distal tip
WO 9~tO5116 216 g ~ 6 9 . PCT~S94/09354 -
.,
. ,
- 18 -
portion 32 becomes deflected from the straight position
shown in Fig. 8 to the deflected position shown in Fig.
9.
Handle body 118 is preferably a single injection
5 molded component composed of nylon or other resilient
material having legs 130 which define channel 132. A
thumb ring 128 is located at one end of handle body 118
to enable an operator to control it, and, if desired,
thumb ring 118 may be rotatable.
Referring more specifically to Fig. 10, actuating
member 124 is slidably disposed on handle body 118
between legs 130 in channel 132. Actuating member 124
preferably is made of nylon, DELRIN~, or any suitable
polymeric injection molded material. Actuating m~mh~r
15 124 may be manufactured as a clam shell with top half 134
and bottom half 136 separately injection molded and later
joined by melting, snap fitting, through the application
of an adhesive such as cyanoacrylate, or clamped together
by legs 130 of handle body 118. As shown in Figs. 8 and
20 9, actuating member 124 preferably has two finger loops
disposed on opposite sides of handle body 118 for
engagement by fingers of an operator.
Pulley surface 126 is disposed on actuating r^mhPr
124 and may be rotary or stationary. In a preferred
25 embodiment, pulley surface 126 defines a rigid, semi-
circular track 156 integral with actuating member 124 and
has a cross section only slightly larger than pull wire
54 to prevent pull wire 54 from buckling under
compressive force.
A biocompatible silicon type lubricant may be used
to reduce friction on pulley surface 126 in embodiments
of the invention employing both fixed and rotatable
pulley surfaces.
The pulley advantage of pulley surface 126, which
35 is in direct contact with pull wire 54, allows the
woss/0sl16 ~ 8g6~ rCT/uss410s3s4
- 19 -
operator to achieve the desired two-to-one activation
ratio in one-h~n~ operation, while the absence of
intervening parts provides the tactile feeling previously
only available in handles with a one to one activation
~ -5 ratio.
Referring now to Fig. 11, pull wire 54 passes
through nose 116 of handle body 118 around pulley surface
126 on actuating member 24, and back to nose 16 where the
end of pull wire 54 is fixed to nose 116. Pull wire 54
10 is confined throughout its entire pathway within medical
device 110 to prevent columnar buckling. Preferably,
c~nmllAe 138 and 140 are used to confine pull wire 54
between nose 116 and actuating member 124. Pull wire 54
is connected, by soldering or any other method, to one
15 end of cannula 138. This end is attached to body 118 by
set screw 142 disposed in can 144 on nose 116. The other
end of c~n~tll~ 138 is telescopically disposed within
actuating member 124. Similarly, cannula 140 has one end
attached to actuating member 124 and the other end
20 telescopically disposed within aperture 146 in nose 116.
C~nnlllAe 138 and 140 are preferably stainless
steel tubes which confine pull wire 54 and allow about
five thousandths of an inch clearance between the inside
wall of the tube and the pull wire. The cannula wall is
25 preferably about two thousandths of an inch thick. The
exterior of cannula 138 and 140 may be coated with an
insulator such as nylon to prevent a person operating the
medical device from being shocked. Alternatively, as
shown in Fig. 10, guard 141 (a part of body 118 which
30 extends outward from legs 130 to cover cannula 138) may
= be included for this same purpose.
Actuation of the snare handle causes pull wire 54
to move about pulley surface 126, through cannula 140 and
out nose 116. Due to the pulley advantage of pulley
35 surface 126, movement of actuating member 124 a given
W095/05116 PCT~S94/09354 ~
2 ~ 6 9
- 20 -
distance 162 results in translation of pull wire 54 twice
the given distance. This two-fold increase in the cable
stroke relative to movement of actuating member 124
permits a nurse with small hands to operate the snare
5 handle with one hand.
